New shorebird population estimates show few increases, consistent long-term declines

Mountain Plover is one of several shorebird species with declining populations. Photo by Mia McPherson

A reassessment of population sizes and trends for all shorebirds that occur in North America has produced higher estimates for 28 of 71 populations and lower estimates for 7 populations.

The numbers matter because they are put to many uses, including setting target population sizes, evaluating the effectiveness of conservation efforts, and identifying Important Bird Areas and wetlands of importance.

Most of the increases, he writes, were the result of more comprehensive surveys or re-analyses of existing data, not actual increases. Only four populations truly grew since 2006: the Atlantic and Great Plains populations of Piping Plover, Hawaiian Stilt, and Upland Sandpiper.

Analysis of data from migration counts and other sources revealed that the proportion of species exhibiting increasing, decreasing, and stable long-term population trends has not changed since 2006. But for many migrants in eastern North America, declines in the 1980s and early 1990s appear to have been followed by stable or increasing numbers.

“Still, the conservation status of North American shorebirds warrants concern,” Andres warns. Consistent declines across all survey methods and time periods are evident in Snowy Plover, Killdeer, Mountain Plover, Lesser Yellowlegs, Whimbrel, Ruddy Turnstone, Red Knot, Sanderling, Semipalmated Sandpiper, Western Sandpiper, Pectoral Sandpiper, Purple Sandpiper, and Dunlin. Worse, a pervasive lack of monitoring data means “we still have virtually no indication of the population trend for 25 percent of the shorebird taxa breeding in North America.”